The invention concerns a device for the insertion and extraction of a cable, particularly an optical transmission cable, into or from a pipe-shaped line.
In the course of the introduction of new cable facilities for telecommunication by regional and local companies, consideration is given increasingly to alternatives to the conventional laying of telecommunication cable underground for economical and/or organizational reasons. One alternative laying technique for telecommunication cable of particular merit especially in economical terms is represented by the use of gas and water lines already in place in the mains of a city or town supply system. Such a solution is detailed in DE 30 01 226 A1. Aside from the reduction of costs associated with establishing a local or regional telecommunication network, the use of existing lines keeps excavation work to a minimum, so that the space assigned to vehicle traffic, which in many cities barely suffices, suffers little restriction. In addition, no significant problem is caused by the density of existing lines serving all conceivable supply and disposal functions, which instead may prove an asset.
For technical and organizational reasons, as well as for reasons connected with the rite of passage, setting up a telecommunication network using cable, with a comparably small exterior diameter, including the possibility of adding participants, who join the network in the future, is best accomplished by laying optical transmission cable in fresh water lines, for example, of the existing supply network. In this respect, it is of great importance to ascertain the drinking water neutrality of the cable material, particularly of the cable coating, as well as to ensure permanent impenetrability of the cable with regard to water steam. In addition, special care must be taken to see that no germ formation or other microbiological contamination occurs while inserting the cable into the line.
An additional difficulty of laying cable is represented by the fact that barriers or other blocking devices are placed at 150-250 m intervals in drinking water lines for the purpose of blocking the fresh water line. Wherever such devices are set up, the cable needs to circumvent the barriers without any compromising implications of a mechanical or optical nature. This is achieved by extracting the cable from the pipe-shaped line before the barrier and reinserting it into the pipe-shaped line behind the barrier. In addition, in order to set up and branch off participant lines, it is necessary to extract an optical cable from the pipe-shaped line or insert it into the pipe-shaped line.